Carburetor



March 12, 1968 S. H. BENMQFEE CARBURETOR Filed Dec. 21, 1966 STA/VA Era BE/VMO/P INVENTOR.

MUM

United States Patent Office 3,372,912 Patented Mar. 12, 1968 3,372,912 CAREURETOR Stanley H. Benmore, Dearhorn, Mich., assignor to Holley Carburetor Company, Warren, Mich, a corporation of Michigan Filed Dec. 21, 1966, Ser. No. 603,514 Claims. (Cl. 261-36) ABSTRACT OF THE DISCLOSURE This application discloses an improved internal combustion engine carburetor in which the fuel supplied to the induction passage is normally metered through a calirbrated jet fed from the fuel bowl in which a predetermined necessary fuel level is maintained by a floatop erated valve controlling the fuel inlet, the improvement comprising a relatively small capacity, heat insulated cavity within the fuel bowl and feeding the jet, the cavity having an overflow positioned slightly below the bowl level and the fuel inlet discharging directly into the small capacity cavity so that it quickly fills to its overflow level and provides an approximately proper fuel level sooner upon cranking of the engine than a comparable level would be reached if the fuel inlet discharged into the larger capacity fuel bowl, the improvement being particularly beneficial in but not limited to carburetors in which the fuel bowl is drained each time the engine is shut down to control air pollution by evaporation, a main benefit being an acceptable cranking time on starting and reduction in undesirable fuel vaporization on hot starting when the fuel bowl must be refilled.

This invention relates generally to internal combustion engine carburetors, and more particularly to a carburetor having means to reduce the cranking time required to start the engine.

The well known current effort to reduce air pollution attributable to automotive vehicles has resulted in a proposal that the carburetor float chamber be drained whenever the engine is shut down to prevent fuel vapors from being released to the atmosphere through the usual float chamber external vent and/or to reduce emission of unburned hydrocarbons through the exhaust system upon restart of the engine due to an overrich mixture produced in the engine induction system by float chamber fuel vapor or percolated fuel being discharged through the internal vent or the main nozzle after an engine shut down.

While draining the carburetor float chamber or fuel bowl each time the engine is shut down will tend to reduce or eliminate the above-mentioned sources of air pollution, a predetermined fuel level is required in the float chamber, and an engine Will obviously not start and continue to run until the required fuel level is attained. Obviously, excessive cranking will be required to cause the fuel pump is refill the float chamber to the required level. In fact, excessive cranking may occur any time the fuel level is substantially reduced, as it might be due to boiling and evaporation after a hot or long engine shut down.

Accordingly, an object of the invention is to provide means for reducing the engine cranking time whenever the carburetor fuel level is so low that excessive cranking would be required.

Another object of this invention is to provide means for minimizing the cranking time of an engine equipped with a carburetor having means for draining the float chamber whenever the engine is shut down.

Another object of the invention is to provide a carburetor wherein the carburetor metering jets are quickly supplied with an adequate fuel head before the entire carburetor float chamber has been refilled to the required predetermined level.

Another object of the invention is to provide a carburetor having a dual cavity float chamber wherein a cavity having a relatively small volume supplying the carburetor metering jet or jets may be quickly filled with fuel initially supplied by the fuel pump upon cranking of the engine.

Another object of the invention is to provide such a carburetor wherein the filling rate of the relatively low volume compartment or cavity is in excess of the fuel required by the engine so that the engine will start and sustain itself on the fuel available in the relatively low volume cavity, the excess fuel spilling over to the larger volume compartment.

Still another object of the invention is to provide such a carburetor wherein the usual float. mechanism controlling the carburetor fuel inlet valve is disposed in the larger volume cavity.

Another object of the invention is to provide such a carburetor wherein the lower volume cavity comprises what may be termed a fuel pocket bafiie defined by a wall having the upper edge thereof or an opening therein disposed just below the required fuel level in the float chamber so that the level of the fuel in the pocket spilling into the main larger volume chamber or cavity is at the required level or within allowable tolerances.

Another object of the invention is to provide such a carburetor wherein the lesser volume cavity or pocket communicates with the larger volume main cavity so that the pocket may be drained when the latter chamber is drained upon engine shut down.

Another object of the invention is to provide means for easily converting certain existing carburetors to carburetors embodying the invention.

Another object of the invention is to provide such a carburetor wherein the so-called pocket or chamber of lesser volume is substantially insulated from engine radiated or conducted heat, thereby eliminating or reducing the tendency of cool fuel to flash or vaporize and produce pressure waves that cause fuel to be forced through the metering jet and out the nozzle, as has been observed to occur when fuel is pumped directly into a hot empty float chamber.

Another object of the invention is to provide a carburetor having means for diverting or directing canburetor inlet fuel to fill the lesser volume fuel pocket.

A still further object of the invention is to provide such a carburetor wherein the fuel pocket baffle of lesser volume is positioned adjacent the carburetor vertical axis, thereby improving carburetor cornering and angularity characteristics by limiting the tendency thereof to lower or raise the fuel head in the metering system.

These and other objects and advantages of the invention will become more apparent when reference is made to the following specification and the accompanying drawings wherein:

FIGURE 1 is a fragmentary cross-sectional view of a carburetor embodying the invention, taken along the plane of line 1-1 of FIGURE 2 and looking in the direction of the arrow;

FIGURE 2 is an exploded perspective view of the carburetor portion shown in FIGURE 1, with portions there of cut away to better illustrate the structure of the invention.

Referring now to the drawings in greater detail, it will be seen that the carburetor 10 shown mounted on the engine 12 is of the type taught by Goodyear, 2,892,622. However, While the invention is shown as applied to a particular carburetor in order to illustrate the ease with which it may be modified to incorporate the invention, it

should be understood that the invention is in no way limited to this particular carburetor and that it is, in fact, easily adapted to any carburetor. It should also be understood that while the invention is particularly adapted for use with carburetors in which the float chamber is drained each time the engine is shut down, it has advantages as already pointed out above, for use in carburetors in which the float chamber is not drained. Since the particular means for draining the float chamber on engine shut down is not a part of this invention, it is not shown. That is, the invention will be described with the understanding that the carburetor may be provided with some means for so draining the float chamber.

A prior art carburetor 10 comprises a body having an induction passage 14 with the usual throttle valve 16 pivotally mounted therein and secured on the engine intake manifold 18, the induction passage also having the usual venturi 20 and a main nozzle 22. One side 24 of the carburetor body is formed so as to have secured thereto a so-called metering block 26 and a fuel bowl cover assembly 28 by means such as the screws 30, with sealing gaskets 32 and 34 therebetween.

The need for the invention can be illustrated by explaining that a prior art carburetor 10 would be assembled without the gasket 36, the fuel pocket bafiie plate 38 and the fuel inlet diverter member 48. Thus, whenever the engine 12 is being cranked or operating, fuel from the tank 42 and the usually engine driven fuel pump 44 enters and flows down the passage 46, past the fuel inlet valve 48, laterally out the openings in the valve seat member 52 and thence into the fuel reservoir 54 in which the float 56 is pivotally mounted. As is well known in the art, the float S6 rises with the rising fuel level in the reservoir 54 and forces the fuel inlet valve 48 upwardly until the valve engages the seat 58 when the required fuel level 60 has been attained, the float force being sufficient to maintain the valve 48 closed against the fuel pressure from the pump 44.

The metering block 26 and the surface 24 of the carburetor body are, of course, formed with appropriate passages and other systems as required for proper functioning of the carburetor. However, in order to simplify the disclosure of the invention, only the main fuel system is shown in FIGURE 1, this main system comprising a passage 62 between the replaceable main jet 64 threaded into the fuel bowl face 66 of the metering block 26 and the main nozzle 22. As is well known in the art, the carburetor 10 is calibrated so that proper quantities of fuel are supplied through the main nozzle 22, provided that the required fuel level 60 is maintained in the fuel reservoir 54. Obviously, if the fuel level is too high or too low, or if the surface of the fuel in the chamber 54 is not level, as would occur when the vehicle is cornered or positioned at a severe angle, the fuel supplied to the engine will be more or less than desired.

It will be understood that the carburetor 10 also includes other fuel systems, such as the idle fuel system (not shown), and that fuel therefor is supplied through the main jet 64 or through passages with openings (not shown) formed in the face 66 of the metering block 26.

It will thus be seen that if a prior art carburetor 10 has the fuel drained therefrom each time the engine is shut down, then the engine 12 will not start and continue to run properly until the float chamber 54 is refilled to the proper level 60 by cranking the engine to operate the pump 44. A primary purpose of the invention is to provide means for reducing such cranking time.

The particular carburetor shown may be modified to incorporate the invention very simple and inexpensively merely be including the additional gasket 36, the pocket baflle plate 38 and the fuel inlet diverter member 40. It will be apparent that the pocket baffle plate 38, which may be stamped sheet metal, molded plastic, etc., when secured against the metering block 26, provides a dual cavity fuel chamber 54. The chamber 68, having a substantially lesser volume than the main float chamber 54 and the 4; wall 70 with the top edge 72 thereof slightly below the desired fuel level 60, encloses the main jet 64 and any other metering orifices (not shown) that must be supplied with fuel.

It will also be noted that the diverter member, which may be formed from any suitable material,when press fitted or otherwise secured on the valve seat member 52, causes fuel entering through the passages 50 to flow through the inner annulus 74 communicating with passages 58 and thence through the passage 76 and into the lesser volume cavity 68.

The capacity of the fuel inlet system is sufficient to quickly fill the fuel pocket chamber 68, maintain the chamber filled to supply starting and running fuel and cause excess fuel to spill over the top edge 72 of the wall 78 and to thus fill the main chamber 54, the level in the chambers 54 and 68 thereafter being controlled, as previously stated, by the well known float or any other suitable structure.

When it is desired to drain the float chamber 54 on engine shut down, by any suitable means represented gen erally by 77, the opening 78 near the bottom of the pocket chamber 68 permits the fuel therein to also be drained, the opening 78 being relatively small so that it does not prevent quick filling of the chamber 68. While a single opening 78 will perform the draining function, it may be desirable to have two or more openings at different levels to control the time required to fill and/ or drain the lesser volume chamber 68.

It is thus apparent that the particular carburetor 10 shown may be very easily adapted to embody the invention merely by assembly the same with the additional gasket 34, pocket baflle plate 38 and fuel diverter member 40. In such a structure, the pocket batlie plate has only a very thin edge thereof exposed to the engine so that heating thereof by heat radiated from the engine is minimized; also, it is separated from the metering block 26 and the fuel bowl cover 28 by gaskets 34 and 36 which tend to insulate the same from conducted heat. Since the wall 70 is relatively cool, the carburetor is less subject to the previously described pressure fluctuations due to flashing or vaporizing of fuel, as compared to a carburetor wherein the intitial fuel is pumped directly into an empty hot fuel bowl.

While the invention is shown as being embodied in a prior art existing carburetor 10 merely by the assembly of the three additional elements, it is, of course, apparent that any carburetor could be formed with the lesser volume cavity 68 in any suitable manner, such as die castin g or otherwise forming the wall 7 0 as an integral part of the carburetor body, merely fitting a separate baffle plate into formed slots, etc., and providing a fuel inlet system that discharges into the lesser volume cavity.

It will also be apparent that the invention provides a quicker starting advantage for any carburetor wherein the fuel level in the float chamber has evaporated, boiled or otherwise become lower than that required for starting. For example, the line XX represents the surface of the fuel in a prior art carburetor without the dual cavity fuel reservoir during a hard left turn or when the vehicle is temporarily inclined, assuming that FIGURE 1 is a view looking toward the front of the engine. Such a disturbance tends to reduce the fuel head and results in a lean mixture supplied to the engine. A disturbance in the opposite direction would, of course, result in a rich mixture.

The line YY, on the other hand, illustrates that in a carburetor embodying the lesser volume cavity 68 adjacent the vertical axis of the carburetor or the metering block 26 there is substantially less tendency for the fuel head to be reduced, even though the attitude of the fuel in the main fuel reservoir 54 is along the line XX, or along any line departing from the horizontal. Thus, the fuel pocket bafile structure contemplated by the invention provides superior cornering and angularity characteristics in any carburetor.

The invention has been shown and described in such clear and concise language as to permit anyone skilled in the art to practice the same. Since modifications are possible within the scope of the invention, no limitations are intended except as recited in the appended claims.

What I claim as my invention is:

1. An internal combustion engine carburetor, comprising a body formed to provide an induction passage having a fuel discharge orifice, a fuel reservoir including a first smaller capacity chamber and a second larger capacity chamber, an inlet for supplying fuel to said reservoir from a source under pressure, means controlling said inlet to maintain a predetermined fuel level in said reservoir, a fuel passage extending between said first chamber and said discharge orifice and including means dependent solely upon the attainment of said predetermined fuel level for metering fuel as required by the engine to said discharge orifice, said inlet discharging fuel directly into said first chamber, said first chamber having an overflow slightly below said predetermined fuel level over which fuel is supplied to said first chamber from said inlet may spill into said second chamber, whereby an approximately correct metering fuel level only slightly below and never exceeding said predetermined fuel level is quickly attained before said predetermined level in said reservoir is reached.

2. A carburetor such as that recited in claim 1, Wherein said first mentioned means is a fioat-controlled valve, said float being disposed in said second chamber.

3. A carburetor such as that recited in claim 1, wherein said metering means in said fuel passage comprises a calibrated restriction.

4. A carburetor such as that recited in claim 1, wherein said metering means is calibrated to meter theoretically correct quantities of fuel only upon the attainment of said predetermined fuel level and is not separately influenced by inlet fuel pressure.

5. A carburetor such as that recited in claim 1, wherein said first cavity into which inlet fuel is discharged is formed so as to be insulated from engine heat when in use and thus normally is at lower temperature than outer walls of said reservoir so as to minimize vaporization of inlet fuel.

6. A carburetor such as that recited in claim 1, wherein the fuel surface area of said first cavity is substantially less than the fuel surface area of said second cavity, whereby disturbances of the fuel level in said first cavity are isolated from and proportionally reduced as compared to disturbances of the fuel level in said second cavity and in said reservoir.

7. A carburetor such as that recited in claim 1, wherein said predetermined fuel level in said fuel reservoir, When attained, exceeds slightly the level of said overflow so that during normal operation fuel metering is determined by said predetermined level and not by a lesser fuel level in said first cavity, the lesser fuel level in said first cavity determining fuel metering only until said predetermined level is reached in said reservoir and said lesser fuel level being reached in said first cavity before it is reached in said second cavity upon filling of said reservoir by overflow from said first cavity.

8. A carburetor such as that recited in claim 1, wherein means is provided for at times draining the fuel from said reservoir, said first cavity having an opening near the bottom thereof communicating with said second cavity so that said first cavity is drained when said reservoir is drained, said opening being restricted so that it serves primarily as a drain and does not substantially reduce the time required to fill said first cavity.

9. A carburetor such as that recited in claim 1, wherein said fuel passage is formed in a separate metering block secured to said body and forming one wall of said reservoir and wherein a member secured on the reservoir side of said metering block and having a portion thereof formed to cooperate with said metering block provides said first cavity having a volume substantially less than the volume of said reservoir and having the reservoir end of said fuel passage disposed therein.

10. A carburetor such as that recited in claim 9, wherein said member is a formed plate secured to said metering block and said reservoir is a hollow body secured to said plate, each with gaskets therebetween.

References Cited UNITED STATES PATENTS 1,748,332 2/1930 Ensign 261-70 2,254,850 9/ 1941 Mallory 261-70 3,127,453 3/1964 Sarto 26172 X FOREIGN PATENTS 631,388 11/1961 Canada. 890,607 3/ 1962 Great Britain. 524,298 4/ 1955 Italy.

HARRY B. THORNTON, Primary Examiner. TIM R. MILES, Examiner. 

